An environmentally benign and selective electrochemical oxidation of sulfides and thiols in a continuous-flow microreactor

Abstract

A practical and environmentally benign electrochemical oxidation of thioethers and thiols in a commercially-available continuous-flow microreactor is presented.

Selective Late‐Stage Oxygenation of Sulfides with Ground‐State Oxygen by Uranyl Photocatalysis

“…[5][6][7] In addition, Nole tal. [8] To the best of our knowledge,n o methods have been developed that efficiently discriminate between the various oxygenation states of sulfur for late-stage synthesis or oxygenation [6b,9] because of the intrinsic limitations of conventional oxygenation strategies. [8] To the best of our knowledge,n o methods have been developed that efficiently discriminate between the various oxygenation states of sulfur for late-stage synthesis or oxygenation [6b,9] because of the intrinsic limitations of conventional oxygenation strategies.…”

“…have developed an electrochemical process conducted in af low reactor. [8] To the best of our knowledge,n o methods have been developed that efficiently discriminate between the various oxygenation states of sulfur for late-stage synthesis or oxygenation [6b,9] because of the intrinsic limitations of conventional oxygenation strategies.…”

Recent Advances in Electrochemical Chalcogen (S/Se)‐Functionalization of Organic Molecules

“…[87] The electrochemical oxidation of thiol derivatives produces the respective disulphides, which can be reduced to thiol-thiolates, depending on the pH, due to the acidity of the thiol. Additionally, Lei and co-workers [88] Recently, Noël and co-workers [89] developed a continuous flow electrochemical procedure to oxidize thiols (e. g. thiophenol, benzylthiol and octanethiol) to give the respective disulphides, as well as to oxidize thioethers to give the respective sulfoxides and sulfones. In 2018, Waldvogel and coworkers [90] developed an electrochemical approach for the SÀ S coupling of dithioanilines 73, providing the cyclic disulphide 1,2-dithiolane derivatives 74, which were isolated in moderate to very good yields (16 examples, 33-87 %), tolerating multiple groups of substituents (Scheme 23).…”

Reusable BNPs‐SiO2@(CH2)3NHSO3H‐catalysed selective oxidation of sulfides to sulfones

“…[14] Boehmite nanoparticles (BNPs) have several advantages, such as non-toxicity, ready availability, high dispersion of active phases, thermal and mechanical stability and high surface area, resulting in high catalyst loading capacity. [19][20][21][22][23][24][25][26][27][28][29][30][31] It should be noted that these procedures have some disadvantages, such as the inability for selective oxidation of sulfides, reactivity towards other functional groups, use of excess amount of oxidant with respect to substrates, lack of reusability of catalyst, use of organic solvents, low yields, expensive oxidants and harsh reaction conditions. [16,17] The derivatives of heteroaryl sulfones constitute core units of many important molecules which are used as drugs and potential precursors [18] (Figure 1).…”

“…Several homogeneous and heterogeneous oxidant-based catalytic systems have been reported for the oxidation of sulfides. [19][20][21][22][23][24][25][26][27][28][29][30][31] It should be noted that these procedures have some disadvantages, such as the inability for selective oxidation of sulfides, reactivity towards other functional groups, use of excess amount of oxidant with respect to substrates, lack of reusability of catalyst, use of organic solvents, low yields, expensive oxidants and harsh reaction conditions. [32][33][34][35] Hydrogen peroxide is an attractive and environmentally benign oxidant for the oxidation of sulfides, because it is inexpensive, easy to handle, safely stored, soluble in water and many organic solvents and produces only water as a side product.…”